The present invention relates to medical devices and, more particularly, to guide wires for positioning and stabilization of intravascular medical devices.
Atherectomy devices are generally designed to remove stenotic occlusions from human arteries and bypass grafts. Atherectomy devices take a number of forms from mechanical cutting devices to various rotating abrading device.
The OAD consists of three stainless steel wires, helically wound to produce a device driveshaft. The OAD has an expanded, eccentric cross-section with an attached diamond surface “crown” located near the distal end. The OAD is revolved at rotational velocities up to 200,000 rpm, with the “crown's” abrasive surface removing stenotic tissue. The Orbital Atherectomy Device is deployed along and rotates around a pre-positioned guide wire.
A current guide wire design is shown in FIG. 1. As seen in the Figure, the guide wire G incorporates a flexible distal tip T that facilitates deployment of the guide wire G through the vascular system. The flexible tip T consists of polytetrafluoroethylene (PTFE) which is commercially available under the name Teflon® from E.I. du Pont de Nemours and Company. The flexible tip T is in the form of heat shrink tubing and is attached to the distal end D of the guide wire G. A flexible, distal, tubular portion P of the tip T can contain embedded platinum marker bands B at specified intervals to enhance radio-opacity. The flexible tip T with marker bands may extend approximately 25-30 mm past the distal end D of the guide wire G. The flexible tip permits the distal end of the guide wire G to be guided in a relatively atraumatic fashion to a desired location within the vasculature of a patient.
The following problems have been observed during deployment of the OAD over the pre-positioned guide wire:
With some prior guide wires, the distal end of the OAD may be extended over the PTFE tubing attached to the distal end of the guide wire shaft.
Further, the contact of the OAD driveshaft with the flexible PTFE tubing has been found to cause torsion and bending failure of the PTFE tubing with the failed segment difficult to extract.
In addition, the rotating OAD driveshaft inner surface creates surface erosion of the PTFE tubing, failing the PTFE tip, friction welding of the OAD to the guide wire, and resulting in premature failure of the OAD and/or the guide wire.
There is a need for an improved OAD guide wire design that addresses the above problems.